Here are a few options for you. Hope this helps! A. To prevent any delay on the painting, a decision will be needed by (enter date). B. It would be beneficial to make an early decision on the painting to avoid having to start the work during the winter. C. If you can decide on the painting by (enter date), this will prevent the work from beginning during the winter. D. To help expedite the process, the painting should be decided on by (enter date). This will prevent the work from starting in the winter. As a native English speaker - "expedite the decision" makes sense but sounds strange and a bit like the scene of a sci-fi movie. I would not use this in formal writing. You could say "you need to be expeditious in your decision" - but that is very formal and not commonly said. Best, Mari